As you've found, Remington doesn't provide any data.
What I've had to do when reloading with either Remington or Winchester bulk bullets is something that goes against the grain of all the warnings that you read in every reloading manual...I mix data.
I'll sit down with as many reloading manuals that I have and find all the data I can find on similar design bullets and the powder that I'm planning on using. I'll chart up data that shows the lowest min load
up to the lowest max load
from each one, then start with the min load and work up slowly being very watchful for high pressure signs.
It's almost like wildcatting since you're in uncharted territory so you have to be very vigilant!
I've never used the Remington 6mm 100gr so I can't give you any starter tips for that specific bullet.
Rem or WW don't have any ballistic data on their bullets either, so once you've got a load worked up you'll have to try it at various distances to get trajectory info for your load.